Conventionally, lamp annealing is included in the annealing methods that are implemented in order to activate impurities ion-implanted in a semiconductor layer and to enable a semiconductor crystal to recover from damage. The lamp annealing is to form an impurity-diffused layer in a semiconductor layer to be treated, by activating, in the presence of nitrogen (N2), impurities in the semiconductor layer through heat treatment with an infrared lamp. For example, in the case of MOS transistor, the lamp annealing has been utilized as a method of heat treatment for impurities implanted in order to reduce parasitic resistance in a gate electrode and source/drain regions, and the like.
In addition, recently, as the annealing for impurities ion-implanted in order to form source/drain regions, laser annealing through laser-beam irradiation has been expected. The laser annealing is heat treatment to heat up a local region in an extremely short time to implement fusion/recrystallization and has advantages in that high electric activation beyond a solid solubility limit, of impurities in a semiconductor, which is ordinarily limited by temperature, can be obtained and that a steep impurity profile can be obtained.
Patent Literature 1
Japanese Patent Application Laid-Open No. 2002-329864
However, in conventional annealing, impurities ion-implanted in a semiconductor layer diffuse outward, whereby the absolute amount of the impurities decreases; in consequence, there are problems in that, in a gate electrode, its depletion is caused, and that, in source/drain regions, the increase of parasitic resistance is caused.
The present invention has been implemented in consideration of the foregoing problems; it is an object of the present invention to realize semiconductor devices that prevent the impurities from diffusing outward and manufacturing method thereof.